METHOD FOR OPERATING A DEVICE FOR WIRELESS TRANSFER OF ENERGY IN THE DIRECTION OF AN ELECTRICAL CONSUMER BY MEANS OF INDUCTIVE COUPLING AND DEVICE

Abstract

Method for operating a device for wireless transfer of energy in the direction of an electrical consumer by means of inductive coupling, wherein the device has: a rectifier for generating a DC voltage from a grid voltage, an inverter fed from the DC voltage, which is designed to generate a pulse-width-modulated actuation signal, a power coil actuated by means of the pulse-width-modulated actuation signal, by means of which a magnetic alternating field can be generated to transfer the energy, and a communication unit, which is designed to exchange data bidirectionally with the electrical consumer, wherein the method has the following steps: sequentially carrying out a power transfer (LTX), a data exchange (DAT), a measurement of setup parameters (MAP), and a measurement of a resonance frequency (MRF), wherein during the power transfer (LTX), an electrical actual power emitted by the inverter is regulated to a predetermined electrical setpoint value, wherein during the data exchange (DAT), data are exchanged between the device and the electrical consumer by means of the communication unit, wherein during the measurement of the setup parameters (MAP), objects possibly arranged over the power coil, in particular foreign obj ects, are detected, wherein during the measurement of the resonance frequency (MRF), a resonance frequency of a resonant circuit having the power coil is ascertained, and wherein the measurement of the resonance frequency (MRF) is executed immediately before or immediately after the measurement of the setup parameters (MAP) or is executed immediately before or immediately after the data exchange (DAT).

Claims

1. Method for operating a device (100) for wireless transfer of energy in the direction of an electrical consumer (200) by means of inductive coupling, wherein the device has: a rectifier (108) for generating a DC voltage (U_S) from a grid voltage (U_N), an inverter (102) fed from the DC voltage (U_S), which is designed to generate a pulse-width-modulated actuation signal (A_S), a power coil (101) actuated by means of the pulse-width-modulated actuation signal (A_S), by means of which a magnetic alternating field can be generated to transfer the energy, and a communication unit (111), which is designed to exchange data bidirectionally with the electrical consumer (200),
wherein the method has the following steps: sequentially carrying out a power transfer (LTX), a data exchange (DAT), a measurement of setup parameters (MAP), and a measurement of a resonance frequency (MRF), wherein during the power transfer (LTX), an electrical actual power emitted by the inverter (102) is regulated to a predetermined electrical setpoint value, wherein during the data exchange (DAT), data are exchanged between the device (100) and the electrical consumer (200) by means of the communication unit (111), wherein during the measurement of the setup parameters (MAP), objects possibly arranged over the power coil (101), in particular foreign objects, are detected, wherein during the measurement of the resonance frequency (MRF), a resonance frequency of a resonant circuit (103) having the power coil (101) is ascertained, and wherein the measurement of the resonance frequency (MRF) is executed immediately before or immediately after the measurement of the setup parameters (MAP) or is executed immediately before or immediately after the data exchange (DAT).

2. Method according to claim 1, characterized in that the data exchange (DAT) and/or the measurement of the setup parameters (MAP) is/are carried out in time ranges in which the grid voltage (U_N) has a zero crossing.

3. Method according to claim 1, characterized in that the measurement of the resonance frequency (MRF) is carried out in time ranges which end 0.5 ms to 2 ms before zero crossing of the grid voltage (U_N) or is carried out in time ranges which begin 0.5 ms to 2 ms after zero crossing of the grid voltage (U_N).

4. Method according to claim 1, characterized in that during the measurement of the resonance frequency (MFR), the inverter (102) is actuated in such a way that the actuation voltage (A_S) is switched over with a detection of a zero crossing of a current (i_s) in the power coil (101).

5. Method according to claim 4, characterized in that if a predetermined peak amperage of the current (i_s) flowing in the power coil (101) is exceeded, the measurement of the resonance frequency (MRF) is ended.

6. Method according to claim 1, characterized in that based on the ascertained resonance frequency, an operating frequency is ascertained using which the power coil (101) is subsequently actuated during the power transfer (LTX).

7. Method according to claim 6, characterized in that the operating frequency is set between 0.5 kHz and 3 kHz greater than the resonance frequency.

8. Method according to claim 6, characterized in that the electrical consumer (200) transfers operating frequency-relevant items of information to the device (100), wherein the operating frequency is set as a function of the resonance frequency and the operating frequency-relevant items of information.

9. Device (100) for wireless transfer of energy in the direction of an electrical consumer (200) by means of inductive coupling, wherein the device has: a rectifier (108) for generating a DC voltage (U_S) from a grid voltage (U_N), an inverter (102) fed from the DC voltage (U_S), which is designed to generate a pulse-width-modulated actuation signal (A_S), a power coil (101) actuated by means of the pulse-width-modulated actuation signal (A_S), by means of which a magnetic alternating field can be generated to transfer the energy, and a communication unit (111), which is designed to exchange data bidirectionally with the electrical consumer (200),
characterized in that the device is designed to carry out a method as claimed in claim 1.

Description

[0071] The invention is described in detail hereinafter with reference to the drawings. In the figures:

[0072] FIG. 1 shows a block diagram of a device for wireless transfer of energy and an associated electrical consumer,

[0073] FIG. 2 shows a schematic time sequence of the method according to the invention, and

[0074] FIG. 3 shows a time curve of a current in a power coil during a half-wave of a grid voltage.

[0075] FIG. 1 shows a block diagram of a device 100 for wireless transfer of energy in the direction of an electrical consumer 200 by means of inductive coupling.

[0076] The device 100 has a rectifier 108 for generating a DC voltage U_S from a conventional single-phase grid voltage U_N of an AC voltage grid 300.

[0077] The device 100 furthermore has an inverter 102 fed from the DC voltage U_S having switching means 109 and 110, which is designed to generate a pulse-width-modulated actuation signal A_S.

[0078] The device 100 furthermore has capacitors 104, 105, which are connected in series between output terminals of the rectifier 108 or the feed voltage U_S, respectively.

[0079] The device 100 furthermore has a power coil 101 actuated by means of the pulse-width-modulated actuation signal A_S, wherein the capacitors 104, 105 and the power coil 101 are interconnected in such a way that they form a resonant circuit 103. For this purpose, one terminal of the power coil 101 is electrically connected to a connecting node of semiconductor switching means 109, 110 of the inverter 102 and another terminal of the power coil 101 is connected to a connecting node of the capacitors 104, 105.

[0080] It is apparent that the illustrated inverter and resonant circuit topology is solely exemplary. For example, an inverter having a full bridge can be used in the scope of the present invention, differently interconnected series or parallel resonant circuits can be used, etc.

[0081] A magnetic alternating field for transferring the energy is generated by means of the power coil 101.

[0082] The device 100 furthermore has a communication unit 111, which is coupled to a communication coil 112. The communication unit 111 in conjunction with the communication coil 112 is used for bidirectional data exchange with the electrical consumer 200.

[0083] The device 100 furthermore has a regulator 116, which is designed to regulate a power emitted by the inverter 102 to a predeterminable setpoint value, wherein a frequency and/or a duty cycle of the actuation signal A_S is/are used as manipulated variable.

[0084] The electrical consumer 200 has a power coil 201 and a passive LC resonant circuit 202 connected downstream.

[0085] The electrical consumer 200 furthermore has a switching unit 203 for changing a load impedance of the electrical consumer 200. The elements 204 and 205 are shown by way of example as loads which can be switched in and out.

[0086] The electrical consumer 200 furthermore has a communication unit 206, which is coupled to a communication coil 207. The communication unit 206 in conjunction with the communication coil 207 is used for bidirectional data exchange with the device 100.

[0087] The electrical consumer 200 furthermore has a control unit 208, which controls the operation of the electrical consumer 200. The control unit 208 has a data connection to the switching unit 203 and the communication unit 206. The control unit 208 controls, inter alia, the synchronized changing of the load impedance by suitable actuation of the switching unit 203 and communication with the device 100.

[0088] FIG. 2 shows a schematic sequence of the method according to the invention over time.

[0089] As shown in FIG. 2, the DC voltage U_S has a half-wave-shaped profile, which corresponds to essentially rectified grid half-waves of the grid voltage U_N.

[0090] In time ranges or slots in which the grid voltage U_N has a zero crossing, either a data exchange DAT between device 100 and consumer 200 or a measurement of setup parameters MAP, also referred to as foreign object detection, FOD, takes place. A power transfer LTX conventionally takes place in between in associated time ranges or slots.

[0091] A measurement of the resonance frequency MRF of the resonant circuit 103 having the power coil 101 takes place immediately before or immediately after the measurement of the setup parameters MAP or immediately before or immediately after the data exchange DAT. In contrast to what is shown in FIG. 2 for illustration purposes, the measurement of the resonance frequency MRF generally does not take place in practice after the data transfer DAT or the measurement of the setup parameters MAP. Instead, the measurement of the resonance frequency MRF takes place at the beginning of the wireless transfer of energy in the direction of the electrical consumer 200 and subsequently upon relevant changes of the power transfer. Relevant changes can represent larger setpoint power jumps, shifting of the consumer 200 with a coupling change, and announced load jumps of the receiver 200, which require a redetermination of the operating frequency.

[0092] The measurement of the resonance frequency MRF takes place in time ranges which end 0.5 ms to 2 ms before a zero crossing of the grid voltage U_N or in time ranges which begin 0.5 ms to 2 ms after a zero crossing of the grid voltage U_N, as shown in FIG. 2.

[0093] During the measurement of the resonance frequency MFR, the inverter 102 is actuated in such a way that the actuation voltage A_S is switched over with a detection of a zero crossing of a current i_s in the power coil 101.

[0094] Based on the ascertained resonance frequency, an operating frequency is set immediately thereafter, using which the power coil 101 is actuated immediately thereafter during the power transfer LTX. The operating frequency is set, for example, between 0.5 kHz and 3 kHz less than the resonance frequency. Furthermore, the electrical consumer 200 can transfer operating frequency-relevant items of information to the device 100, wherein the operating frequency is set as a function of the resonance frequency and the operating frequency-relevant items of information.

[0095] FIG. 3 shows a time curve of the current i_s in the power coil 101 during a half-wave of the grid voltage UN at 50 Hz.

[0096] In a slot between 0 ms and 1 ms, a data exchange DAT takes place between the device 100 and the consumer 200 via their communication coils 112 and 207, respectively.

[0097] In a slot between 1 ms and 1.5 ms, the measurement of the resonance frequency MRF takes place.

[0098] In a slot between 1.5 ms and 9 ms shortly before the end of the grid half-wave, the power transfer LTX takes place at an operating frequency which is set as a function of the measured resonance frequency.

[0099] At 9 ms, the power transfer is interrupted and the next slot is started for a next data transfer or for measuring setup parameters.